Extracellular proteins play important roles in, among other things, the formation, differentiation and maintenance of multicellular organisms. The fate of many individual cells, e.g., proliferation, migration, differentiation, or interaction with other cells, is typically governed by information received from other cells and/or the immediate environment. This information is often transmitted by secreted polypeptides (for instance, mitogenic factors, survival factors, cytotoxic factors, differentiation factors, neuropeptides, and hormones) which are, in turn, received and interpreted by diverse cell receptors or membrane-bound proteins. These secreted polypeptides or signaling molecules normally pass through the cellular secretory pathway to reach their site of action in the extracellular environment.
Secreted proteins have various industrial applications, including as pharmaceuticals, diagnostics, biosensors and bioreactors. Most protein drugs available at present, such as thrombolytic agents, interferons, interleukins, erythropoietins, colony stimulating factors, and various other cytokines, are secretory proteins. Their receptors, which are membrane proteins, also have potential as therapeutic or diagnostic agents. Efforts are being undertaken by both industry and academia to identify new, native secreted proteins. Many efforts are focused on the screening of mammalian recombinant DNA libraries to identify the coding sequences for novel secreted proteins. Examples of screening methods and techniques are described in the literature [see, for example, Klein et al., Proc. Natl. Acad. Sci. 93:7108-7113 (1996); U.S. Pat. No. 5,536,637)].
Membrane-bound proteins and receptors can play important roles in, among other things, the formation, differentiation and maintenance of multicellular organisms. The fate of many individual cells, e.g., proliferation, migration, differentiation, or interaction with other cells, is typically governed by information received from other cells and/or the immediate environment. This information is often transmitted by secreted polypeptides (for instance, mitogenic factors, survival factors, cytotoxic factors, differentiation factors, neuropeptides, and hormones) which are, in turn, received and interpreted by diverse cell receptors or membrane-bound proteins. Such membrane-bound proteins and cell receptors include, but are not limited to, cytokine receptors, receptor kinases, receptor phosphatases, receptors involved in cell—cell interactions, and cellular adhesin molecules like selectins and integrins. For instance, transduction of signals that regulate cell growth and differentiation is regulated in part by phosphorylation of various cellular proteins. Protein tyrosine kinases, enzymes that catalyze that process, can also act as growth factor receptors. Examples include fibroblast growth factor receptor and nerve growth factor receptor.
Membrane-bound proteins and receptor molecules have various industrial applications, including as pharmaceutical and diagnostic agents. Receptor immunoadhesins, for instance, can be employed as therapeutic agents to block receptor-ligand interactions. The membrane-bound proteins can also be employed for screening of potential peptide or small molecule inhibitors of the relevant receptor/ligand interaction.
Efforts are being undertaken by both industry and academia to identify new, native receptor or membrane-bound proteins. Many efforts are focused on the screening of mammalian recombinant DNA libraries to identify the coding sequences for novel receptor or membrane-bound proteins.
1. PRO1800
Hep27 protein is synthesized and accumulated in the nucleus of human hepatoblastoma cells (HepG2 cells) following growth arrest induced by butyrate treatment (Gabrielli et al., Eur. J. Biochem. 232:473-477 (1995)). The synthesis of Hep27 is inhibited in cells that, released from the butyrate block, have resumed DNA synthesis. The Hep27 protein sequence shows significant homology to the known short-chain alcohol dehydrogenase (SCAD) family of proteins and it has been suggested that Hep27 is a new member of the SCAD family of proteins. In agreement with its nuclear localization, Hep27 has a region similar to the bipartite nuclear-targeting sequence and Hep27 mRNA expression and protein synthesis suggests the existence of a regulation at the post-transcriptional level.
We herein describe the identification and characterization of novel polypeptides having homology to Hep27 protein, designated herein as PRO1800 polypeptides.
2. PRO539
Development of multicellular organisms depends, at least in part, on mechanisms which specify, direct or maintain positional information to pattern cells, tissues, or organs. Various secreted signaling molecules, such as members of the transforming growth factor-beta (TGF-β), Wnt, fibroblast growth factors and hedgehog families have been associated with patterning activity of different cells and structures in Drosophila as well as in vertebrates. Perrimon, Cell 80:517-520 (1995).
Costal-2 is a novel kinesin-related protein in the Hedgehog signaling pathway. Hedgehog (Hh) was first identified as a segment-polarity gene by a genetic screen in Drosophila melanogaster, Nusslein-Volhard et al. Roux. Arch. Dev. Biol. 193: 267-282 (1984), that plays a wide variety of developmental functions. Perrimon, supra. Although only one Drosophila Hh gene has been identified, three mammalian Hh homologues have been isolated: Sonic Hh (SHh), Desert Hh (DHh) and Indian Hh (IHh), Echelard et al., Cell 75: 1417-30 (1993); Riddle et al., Cell 75: 1401-16 (1993). SHh is expressed at high level in the notochord and floor plate of developing vertebrate embryos. In vitro explant assays as well as ectopic expression of SHh in transgenic animals show that SHh plays a key role in neuronal tube patterning, Echelard et al., supra., Krauss et al., Cell 75, 1432-44 (1993), Riddle et al., Cell 75: 1401-16 (1993), Roelink et al, Cell 81: 445-55 (1995). In vitro explant assays as well as ectopic expression of SHh in transgenic animals show that SHh plays a key role in neural tube patterning, Echelard et al. (1993), supra.; Ericson et al., Cell 81: 747-56 (1995); Marti et al., Nature 375: 322-5 (1995); Roelink et al. (1995), supra; Hynes et al., Neuron 19: 15-26 (1997). Hh also plays a role in the development of limbs (Krauss et al., Cell 75: 1431-44 (1993); Laufer et al., Cell 79, 993-1003 (1994)), somites (Fan and Tessier-Lavigne, Cell 79, 1175-86 (1994); Johnson et al., Cell 79: 1165-73 (1994)), lungs (Bellusci et al., Develop. 124: 53-63 (1997) and skin (Oro et al., Science 276: 817-21 (1997). Likewise, IHh and DHh are involved in bone, gut and germinal cell development, Apelqvist et al., Curr. Biol. 7: 801-4 (1997); Bellusci et al., Dev. Suppl. 124: 53-63 (1997); Bitgood et al., Curr. Biol. 6: 298-304 (1996); Roberts et al., Development 121: 3163-74 (1995). SHh knockout mice further strengthened the notion that SHh is critical to many aspect of vertebrate development, Chiang et al., Nature 383: 407-13 (1996). These mice show defects in midline structures such as the notochord and the floor plate, absence of ventral cell types in neural tube, absence of distal limb structures, cyclopia, and absence of the spinal column and most of the ribs.
At the cell surface, the Hh signals is thought to be relayed by the 12 transmembrane domain protein Patched (Ptch) [Hooper and Scott, Cell 59: 751-65 (1989); Nakano et al., Nature 341: 508-13 (1989)] and the G-protein coupled like receptor Smoothened (Smo) [Alcedo et al., Cell 86: 221-232 (1996); van den Heuvel and Ingham, Nature 382: 547-551 (1996)]. Both genetic and biochemical evidence support a receptor model where Ptch and Smo are part of a multicomponent receptor complex, Chen and Struhl, Cell 87: 553-63 (1996); Marigo et al., Nature 384: 176-9 (1996); Stone et al., Nature 384: 129-34 (1996). Upon binding of Hh to Ptch, the normal inhibitory effect of Ptch on Smo is relieved, allowing Smo to transduce the Hh signal across the plasma membrane. Loss of function mutations in the Ptch gene have been identified in patients with the basal cell nevus syndrome (BCNS), a hereditary disease characterized by multiple basal cell carcinomas (BCCs). Disfunctional Ptch gene mutations have also been associated with a large percentage of sporadic basal cell carcinoma tumors, Chidambaram et al., Cancer Research 56: 4599-601 (1996); Gailani et al., Nature Genet. 14: 78-81 (1996); Hahn et al., Cell 85: 841-51 (1996); Johnson et al., Science 272: 1668-71 (1996); Unden et al., Cancer Res. 56: 4562-5; Wicking et al., Am. J. Hum. Genet. 60: 21-6 (1997). Loss of Ptch function is thought to cause an uncontrolled Smo signaling in basal cell carcinoma. Similarly, activating Smo mutations have been identified in sporatic BCC tumors (Xie et al., Nature 391: 90-2 (1998)), emphasizing the role of Smo as the signaling subunit in the receptor complex for SHh. However, the exact mechanism by which Ptch controls Smo activity still has yet to be clarified and the signaling mechanisms by which the Hh signal is transmitted from the receptor to downstream targets also remain to be elucidated. Genetic epistatic analysis in Drosophila has identified several segment-polarity genes which appear to function as components of the Hh signal transduction pathway, Ingham, Curr. Opin. Genet. Dev. 5: 492-8 (1995); Perrimon, supra. These include a kinesin-like molecule, Costal-2 (Cos-2) [Robbins et al., Cell 90: 225-34 (1997); Sisson et al., Cell 90: 235-45 (1997)], a protein designated fused [Preat et al., Genetics 135: 1047-62 (1990); Therond et al., Proc. Natl Acad Sci. USA 93: 4224-8 (1996)], a novel molecule with unknown function designated Suppressor of fused [Pham et al., Genetics 140: 587-98 (1995); Preat, Genetics 132: 725-36 (1992)] and a zinc finger protein Ci. [Alexandre et al., Genes Dev. 10: 2003-13 (1996); Dominguez et al., Science 272: 1621-5 (1996); Orenic et al, Genes Dev. 4: 1053-67 (1990)]. Additional elements implicated in Hh signaling include the transcription factor CBP [Akimaru et al., Nature 386: 735-738 (1997)], the negative regulator slimb [Jiang and Struhl, Nature 391: 493-496 (1998)] and the SHh response element COUP-TFII [Krishnan et al., Science 278: 1947-1950 (1997)].
Mutants in Cos-2 are embryonicly lethal and display a phenotype similar to Hh over expression, including duplications of the central component of each segment and expansion domain of Hh responsive genes. In contrast, mutant embryos for fused and Ci show a phenotype similar to Hh loss of function including deletion of the posterior part of each segment and replacement of a mirror-like image duplication of the anterior part or each segment and replacement of a mirror-like duplication of the anterior part, Busson et al., Roux. Arch. Dev. Biol. 197: 221-230 (1988). Molecular characterizations of Ci suggested that it is a transcription factor which directly activates Hh responsive genes such as Wingless and Dpp, Alexandre et al., (1996) supra, Dominguez et al., (1996) supra. Likewise, molecular analysis of fused reveals that it is structurally related to serine threonine kinases and that both intact N-terminal kinase domain and a C-terminal regulatory region are required for its proper function, Preat et al., Nature 347: 87-9 (1990); Robbins et al., (1997), supra; Therond et al., Proc. Natl. Acad. Sci. USA 93: 4224-8 (1996). Consistent with the putative opposing functions of Cos-2 and fused, fused mutations are suppressed by Cos-2 mutants and also by Suppressor of fused mutants, Preat et al., Genetics 135: 1047-62 (1993). However, whereas fused null mutations and N-terminal kinase domain mutations can be fully suppressed by Suppressor of fused mutations, C-terminus mutations of fused display a strong Cos-2 phenotype in a Suppressor of fused background. This suggests that the fused kinase domain can act as a constitutive activator of SHh signaling when Suppressor of Fused is not present. Recent studies have shown that the 92 kDa Drosophila fused, Cos-2 and Ci are present in a microtubule associated multiprotein complex and that Hh signaling leads to dissociation of this complex from microtubules, Robbins et al, Cell 90: 225-34 (1997); Sisson et al., Cell 90: 235-45 (1997). Both fused and Cos-2 become phosphorylated in response to Hh treatment, Robbins et al., supra; Therond et al., Genetics 142: 1181-98 (1996), but the kinase(s) responsible for this activity(ies) remain to be characterized. To date, the only known vertebrate homologues for these components are members of the Gli protein family (e.g., Gli-1, Gli-2 and Gli-3). These are zinc finger putative transcription factors that are structurally related to Ci. Among these, Gli-1 was shown to be a candidate mediator of the SHh signal [Hynes et al., Neuron 15: 35-44 (1995), Lee et al., Development 124: 2537-52 (1997); Alexandre et al., Genes Dev. 10: 2003-13 (1996)] suggesting that the mechanism of gene activation in response to Hh may be conserved between fly and vertebrates. To determine whether other signaling components in the Hh cascade are evolutionarily conserved and to examine the function of fused in the Hh signaling cascade on the biochemical level, Applicants have isolated and characterized the human fused cDNA. Tissue distribution on the mouse indicates that fused is expressed in SHh responsive tissues. Biochemical studies demonstrate that fused is a functional kinase. Functional studies provide evidence that fused is an activator of Gli and that a dominant negative form of fused is capable of blocking SHh signaling in Xenopus embryos. Together this data demonstrated that both Cos-2 and fused are directly involved in Hh signaling.
For additional references related to the Costal-2 protein, see Simpson et al., Dev. Biol. 122:201-209 (1987), Grau et al., Dev. Biol. 122:186-200 (1987), Preat et al., Genetics 135:1047-1062 (1993), Sisson et al., Cell 90:235-245 (1997) and Robbins et al., Cell 90:225-234 (1997).
Applicants have herein identified and describe a cDNA encoding a human Costal-2 homolog polypeptide, designated herein as PRO539.
3. PRO982
Efforts are being undertaken by both industry and academia to identify new, native secreted proteins. Many efforts are focused on the screening of mammalian recombinant DNA libraries to identify the coding sequences for novel secreted proteins. We herein describe the identification and characterization of novel secreted polypeptides, designated herein as PRO982 polypeptides.
4. PRO1434
The nel gene has been described to encode a protein that is expressed in the neural tissues of chicken (Watanabe et al., Genomics 38(3):273-276 (1996)). Recently, two novel human cDNAs (designated NELL1 and NELL2) have been isolated and characterized which encode polypeptides having homology to that encoded by the chicken nel gene, wherein those human polypeptides contain six EGF-like repeats (Watanabe et al., supra). Given the neural-specific expression of these genes, it is suggested that they may play a role in neural development. There is, therefore, significant interest in identifying and characterizing novel polypeptides having homology to net, NELL1 and NELL2.
We herein describe the identification and characterization of novel polypeptides having homology to the net protein, designated herein as PRO1434 polypeptides.
5. PRO1863
Efforts are being undertaken by both industry and academia to identify new, native transmembrane proteins. Many efforts are focused on the screening of mammalian recombinant DNA libraries to identify the coding sequences for novel transmembrane proteins. We herein describe the identification and characterization of novel transmembrane polypeptides, designated herein as PRO1863 polypeptides.
6. PRO1917
The characterization of inositol phosphatases is of interest because it is fundamental to the understanding of signaling activities that stimulate the release of Ca2+ from the endoplasmic reticulum. Molecular cloning allowed the identification of a multiple inositol polyphosphate phosphatase which is highly expressed in kidney and liver (Craxton et al. (1997) Biochem J. 328:75-81).
7. PRO1868
The inflammatory response is complex and is mediated by a variety of signaling molecules produced locally by mast cells, nerve endings, platelets, leucocytes and complement activation. Certain of these signaling molecules cause the endothelial cell lining to become more porous and/or even to express selectins which act as cell surface molecules which recognize and attract leucocytes through specific carbohydrate recognition. Stronger leucocyte binding is mediated by integrins, which mediate leukocyte movement through the endothelium. Additional signaling molecules act as chemoattractants, causing the bound leucocytes to crawl towards the source of the attractant. Other signaling molecules produced in the course of an inflammatory response escape into the blood and stimulate the bone marrow to produce more leucocytes and release them into the blood stream.
Inflammation is typically initiated by an antigen, which can be virtually any molecule capable of initiating an immune response. Under normal physiological conditions these are foreign molecules, but molecules generated by the organism itself can serve as the catalyst as is known to occur in various disease states.
T-cell proliferation is a mixed lymphocyte culture or mixed lymphocyte reaction (MLR) is an established indication of the ability of a compound to stimulate the immune system. In an inflammatory response, the responding leucocytes can be neutrophilic, eosinophilic, monocytic or lymphocytic. Histological examination of the affected tissues provides evidence of an immune stimulating or inhibiting response. See Current Protocols in Immunology, ed. John E. Coligan, 1994, John Wiley and Sons, Inc.
Inflammatory bowel disease (IBD) is a term used to collectively describe gut disorders including both ulcerative colitis (UC) and Crohn's disease, both of which are classified as distinct disorders, but share common features and likely share pathology. The commonality of the diagnostic criteria can make it difficult to precisely determine which of the two disorders a patient has; however the type and location of the lesion in each are typically different. UC lesions are characteristically a superficial ulcer of the mucosa and appear in the colon, proximal to the rectum. CD lesions are characteristically extensive linear fissures, and can appear anywhere in the bowel, occasionally involving the stomach, esophagus and duodenum.
Conventional treatments for IBD usually involve the administration of antiinflammatory or immunosuppressive agents, such as sulfasalazine, corticosteriods, 6-mercaptopurine/azathoprine, or cyclospoine all of which only bring partial relief to the afflicted patient. However, when antiinflammatory/immunosuppressive therapies fail, colectomies are the last line of defense. Surgery is required for about 30% of CD patients within the first year after diagnosis, with the likelihood for operative procedure increasing about 5% annually thereafter. Unfortunately, CD also has a high rate of reoccurrence as about 5% of patients require subsequent surgery after the initial year. UC patients further have a substantially increased risk of developing colorectal cancer. Presumably, this is due to the recurrent cycles of injury to the epithelium, followed by regrowth, which continually increases the risk of neoplastic transformation.
A recently discovered member of the immunoglobulin superfamily known as Junctional Adhesion Molecule (JAM) has been identified to be selectively concentrated at intercellular junctions of endothelial and epithelial cells of different origins. Martin-Padura, I. et al., J. Cell Biol. 142(1): 117-27 (1998). JAM is a type I integral membrane protein with two extracellular, intrachain disulfide loops of the V-type. JAM bears substantial homology to A33 antigen (FIG. 1 or FIG. 18). A monoclonal antibody directed to JAM was found to inhibit spontaneous and chemokine-induced monocyte transmigration through an endothelial cell monolayer in vitro. Martin-Padura, supra.
It has been recently discovered that JAM expression is increased in the colon of CRF2-4-/-mice with colitis. CRF2-4-/-(IL-10R subunit knockout mice) develop a spontaneous colitis mediated by lymphocytes, monocytes and neutrophils. Several of the animals also developed colon adenocarcinoma. As a result, it is foreseeable likely that the compounds of the invention are expressed in elevated levels in or otherwise associated with human diseases such as inflammatory bowel disease, other inflammatory diseases of the gut as well as colorectal carcinoma.
The compounds of the invention also bear significant homology to A33 antigen, a known colorectal cancer-associated marker. The A33 antigen is expressed in more than 90% of primary or metastatic colon cancers as well as normal colon epithelium. In carcinomas originating from the colonic mucosa, the A33 antigen is expressed homogeneously in more than 95% of all cases. The A33 antigen, however, has not been detected in a wide range of other normal issues, i.e., its expression appears to be organ specific. Therefore, the A33 antigen appears to play an important role in the induction of colorectal cancer.
Since colon cancer is a widespread disease, early diagnosis and treatment is an important medical goal. Diagnosis and treatment of colon cancer can be implemented using monoclonal antibodies (mAbs) specific therefore having fluorescent, nuclear magnetic or radioactive tags. Radioactive gene, toxins and/or drug tagged mAbs can be used for treatment in situ with minimal patient description. mAbs can also be used to diagnose during the diagnosis and treatment of colon cancers. For example, when the serum levels of the A33 antigen are elevated in a patient, a drop of the levels after surgery would indicate the tumor resection was successful. On the other hand, a subsequent rise in serum A33 antigen levels after surgery would indicate that metastases of the original tumor may have formed or that new primary tumors may have appeared.
Such monoclonal antibodies can be used in lieu of, or in conjunction with surgery and/or other chemotherapies. For example, preclinical analysis and localization studies in patients infected with colorectal carcinoma with a mAb to A33 are described in Welt et al., J. Clin. Oncol. 8: 1894-1906 (1990) and Welt et al., J. Clin. Oncol. 12: 1561-1571 (1994), while U.S. Pat. No. 4,579,827 and U.S. Ser. No. 424,991 (E.P. 199,141) are directed to the therapeutic administration of monoclonal antibodies, the latter of which relates to the application of anti-A33 mAb.
We herein describe the identification and characterization of novel polypeptides having homology to A33 antigen protein, designated herein as PRO1868 polypeptides.
8. PRO3434
Efforts are being undertaken by both industry and academia to identify new, native secreted proteins. Many efforts are focused on the screening of mammalian recombinant DNA libraries to identify the coding sequences for novel secreted proteins. We herein describe the identification and characterization of novel secreted polypeptides, designated herein as PRO3434 polypeptides.
9. PRO1927
Proteins are glycosylated by a complex set of reactions which are mediated by membrane bound glycosyltransferases. There is a large number of different glycosyltransferases that account for the array of carbohydrate structures synthesized. N-acetylglucosaminyltransferase proteins comprise a family of glycosyltransferases that provide for a variety of important biological functions in the mammalian organism. As an example, UDP-N-acetylglucosamine: alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I is an glycosyltransferase that catalyzes an essential first step in the conversion of high-mannose N-glycans to hybrid and complex N-glycans (Sarkar et al., Proc. Natl. Acad. Sci. USA. 88:234-238 (1991). UPD-N-acetylglucosamine:alpha1, 3-D-mannoside beta1, 4-N-acetylglucosaminyltransferase is an essential enzyme in the production of tri- and tetra-antennary asparagine-linked sugar chains, and has been recently been purified from bovine small intestine using cDNA cloning (Minowa et al., J. Biol. Chem. (1998) 273(19): 11556-62). There is interest in the identification and characterization of additional members of the N-acetylglucosaminyltransferase protein family, and more generally, the identification of novel glycosyltransferases.